1. Field of the Disclosure
The present disclosure relates generally to wireless communication systems and, in particular, to network assisted interference cancellation in wireless communication systems.
2. Description of the Related Art
Heterogeneous wireless communication systems typically include a variety of different types of cells deployed in an overlay configuration. For example, a heterogeneous wireless communication system may include macrocells for providing wireless connectivity over relatively large areas and one or more smaller cells for providing wireless connectivity over relatively small areas within the larger areas covered by the macrocells. The macrocells may include base station, base station routers, and the like. The smaller cells may include low power nodes, microcells, femtocells, picocells, access points, home base station routers, and the like. The terms “cell,” “macrocell,” “microcell,” etc. are conventionally used to indicate both the physical device used to provide wireless connectivity and the coverage area of the wireless connectivity. Thus, the term “macrocell” may refer to a base station that provides wireless connectivity for the coverage area of the base station. User equipment can communicate with the wireless communication system over downlink (or forward link) channels that convey information from the network to the user equipment or uplink (or reverse link) channels that convey information from the user equipment to the network.
User equipment can be offloaded from the macrocells to the smaller cells to improve the overall capacity of the heterogeneous wireless communication system. For example, user equipment may hand off from the macrocell to a smaller cell when the signal-to-interference-plus-noise ratios (SINR) of signals received at the user equipment from the macrocell are smaller than the SINR of signals received at the user equipment from the smaller cell. Biasing can be applied to force user equipment to hand over to the smaller cells at lower SINRs than in typical handovers between macrocells. Biasing expands the coverage area of the smaller cells and can cause more user equipment to be offloaded from the macrocells to the smaller cells. Thus, biasing may further increase the capacity of the heterogeneous wireless communities in system. However, user equipment that hands off from a macrocell to a smaller cell may receive strong interfering signals from the macrocell, particularly when the user equipment is in the expanded range of the smaller cell.